Rafael Nadal was handed a walkover to the semi-finals of the Melbourne Summer Set tournament when his opponent withdrew with a foot injury.

In an ironic development, given Nadal has been so plagued by his own serious foot problems, Tallon Griekspoor had to pull out of his scheduled clash with the 20-time grand slam champion on Friday.

That was perhaps not the news Nadal wanted, given the Spaniard is competing this week to gain much-needed match practice ahead of the Australian Open. It is his first ATP Tour event since August, when a long-existing left foot problem caused him to curtail his season.

Withdrawing from a Rod Laver Arena tussle with Nadal was a painful blow to 25-year-old Dutchman Griekspoor too, and he wrote on Twitter: "These are the matches you play for."

It would have been a first career meeting with all-time great Nadal for the world number 65, who instead faces a fitness battle before the first grand slam of the year begins on January 17.

Nadal will go on to face Finland's Emil Ruusuvuori, who won 6-2 6-1 against Slovakian Alex Molcan. The other semi-final on Saturday will see Bulgarian third seed Grigor Dimitrov tackle American qualifier Maxime Cressy.

At the Adelaide International, the top three seeds sauntered through to the semi-finals. Top seed Gael Monfils brushed aside Tommy Paul 6-4 6-1, number two Karen Khachanov saw off Egor Gerasimov 7-5 6-3, and third seed Marin Cilic was a 6-3 6-2 winner over Laslo Djere.

It was also confirmed on Friday that former world number one Andy Murray has been awarded a wildcard into next week's Sydney Classic.

Murray suffered a first-round exit in Melbourne and is looking for a run of matches before launching his campaign at the Australian Open, where he is a five-time runner-up.